This image was made in January 2016 and it is the first time I ever used vectors.  
I realize that there are some proportions and perspective issues with Rainbow Dash in particular and Twilight too comes with some flaws.  
Thanks and credit for many of the Ponyville buildings in the background goes to JavKiller :)  
I integrated a little easter egg referring to another franchise in this image and I am curios if anyone will spot it ;)  
The image is a scene from chapter 31 (pages 133 / 134) of my fanfiction Lessons in Quirks  
This is the respective passage (torn out of context but giving an idea of what is going on):  

 
Rainbow Dash gave her a broad smile and as Twilight meant to return it, she noticed that she was smiling already anyway. The sensation of being carried by the air was uplifting in every sense of the word.
 
“Very good, Twilight!” Rainbow Dash said. “This doesn’t work as well at any time of course. Only when it is so warm as it is right now and it doesn’t work as well the higher up we go. So let’s get up a little higher, shall we?”
 
“Must we, Rainbow? It’s so nice down here and if this doesn’t work as well the higher up we go…”
 
“Come on now, don’t be such a chicken! You do want to learn something new, don’t you?”
 
Rainbow Dash sure knew which buttons she had to press. Angling her wings a little more, Twilight began to ascend. Rainbow Dash however bolted upright pretty much on the spot almost like a missile. Twilight gazed after her rainbow track, feeling a little hopeless. This bolting upright seemed to defy every law of aerodynamics and gravity she had ever read about. She struggled to ascend in a steeper angle, but the steeper she got the slower she became and from one point on which wasn’t even close to vertical it felt like she was suspended from some invisible thread rather than gaining any height, in fact she felt that she was slowly descending, no matter how hard she flapped.
 
“Easy Twilight”, Rainbow’s voice said right beside her. Once again Twilight hadn’t noticed her approach at all. She had been so focused on her struggle to gain altitude that a flock of dragons could have flown by without her noticing. At least she was so exhausted from the effort that the sudden address by Rainbow Dash didn’t give her another downing-initiating start.
 
“What are you doing?” Rainbow Dash asked. There was no mock in her voice.
 
“I can’t do it! I cannot bolt up like that, Rainbow!” Twilight’s voice was slightly trembling, half from the effort, half from disappointment in herself.
 
“No, Twilight, and you don’t have to. Many pegasi can’t do that. I was just flying ahead to test the airs up there to see what we got. I didn’t expect you to follow me like that.”
 
Somewhat reassured Twilight asked: “So how am I to do it, Rainbow?”
 
“I think you should just screw yourself up”, Rainbow Dash said matter-of-factly.
 
Twilight goggled at her. “I beg your pardon?”
 
“Like this”, Rainbow Dash said in blissful ignorance of the little shock she had given Twilight. Flapping a little faster with one wing than with the other and leaning a little sideways, Rainbow Dash began to fly upwards in spirals much like she was following the threads of a screw.
 
“It’s an easy way to gain height on the spot”, Rainbow Dash explained. “It is also a nice little practice in flying curves, in overcoming dizziness and in flapping your wings at different speed. I think some eggheaded flying instructor called this ‘asynchrous flapping’ or something like that.” “Asynchronous flapping?” Twilight suggested.
 
“Yeah whatever. Come on up now!”